When a microwave filter consisting of vertical parallel metal rods is in the absorbing position, oscillating currents are set up in the rods. At any one instant, the current in each rod has the same magnitude and direction. At that instant

a. the rods will try to shift vertically downwards.
b. the rods will try to move together horizontally.
c. the rods will try to shift vertically upwards.
d. the rods will try to move apart horizontally.
d. the rods will not be affected because the source of current is not a battery.